10 BULLETIN 940, U. S. DEPARTMENT OF AGRICULTURE. 



largely eliminated peptonization and made the stormy reaction more 

 clear-cut, but at the same time reduced the number of positive tests, 

 probably because of an inhibiting action on B. enteritidis sporogenes. 

 With a strength of 1 to 100,000 the gentian violet caused no reduction 

 in the number of positive tests, but also had no effect in eliminating 

 peptonization in samples containing facultative anaerobes capable of 

 producing this reaction. While peptonization in occasional tubes is 

 not a very serious matter, it tends to create difficulty in determining 

 "whether a tube shows a typical stormy fermentation. The use of 

 gentian violet proved to be of no assistance in this connection. 



Henry (6) made use of alkaline egg albumen in connection with 

 the development of B. welchii on solid media and obtained beneficial 

 results. It was thought, therefore, that it might be possible to use 

 this in. connection with the sporogenes test in order to stimulate the 

 growth of these organisms. The alkaline egg medium as given by 

 Henry is as follows : 



To the whites of two eggs 4 c. c. of N/1 NaOH is added and the 

 mixture heated at about 95° C. for 1^ hours. Solution is then made 

 up to 330 c. c. volume with water and then filtered and sterilized. 

 When using the sporogenes test with 10 tubes of 2 c. c. each of milk, 

 1 c. c. of sterile, alkaline egg solution was added to each tube before 

 the milk. The tubes were then heated and carried through the test 

 in the usual manner. In some samples of milk it was found that 

 when alkaline egg was used the number of positive tubes in the set 

 of 10 was considerably increased. Quite often the reaction appeared 

 more quickly than in the tubes without the egg solution and as a rule 

 the reaction was more vigorous. This likely improvement in the test 

 did not follow consistently, however, in all samples, and it was found 

 that the advantage gained did not compensate for the additional 

 trouble of using the alkaline egg solution. 



The effect of the addition of peptone on the sporogenes test was 

 also tried. In this experiment 10 tubes, each containing 10 c. c. of 

 milk, were used instead of the 2 c. c. amounts used by Savage. Two 

 series of tubes of 10 c. c. each were prepared, one series containing 

 approximately 5 per cent peptone and the other containing none. 

 One c. c. of a sterile 5 per cent solution of peptone was placed in each 

 tube of the peptone series, to each of which was then added 10 c. c. 

 of milk. Nineteen samples of milk were examined on this compara- 

 tive basis and the results indicated that in some cases the addition of 

 peptone caused an increase in the number of positive tubes and also 

 a more vigorous reaction. In other samples the number of positive 

 reactions was lower in the milk with peptone than in that without. 

 On the whole, the results indicated that there was no particular ad- 

 vantage in the addition of the peptone solution. 



